Here's What Actually Happens in a Nuclear Fusion Reactor

The Sun may engage in nuclear fusion like it's no big deal, but attempting to make it happen here on Earth is perhaps one of the largest challenges that faces scientists today. On Earth, you can't rely on the mass of a giant star to help you out, and you also have to worry about creating, maintaining, and sustaining streams of super hot plasma without letting them die out or destroy everything around them.

Because plasma is an incredibly hot and high-energy state of matter, physical materials aren't fit to contain it. Instead, fusion reactors rely on magnetic fields to manipulate the plasma and keep it in check. This awesome little demonstration from The Royal Institution shows exactly what that kind of manipulation looks like:

Related Stories

This trick is obviously useful to keep hot plasma away from the surface of the structure that is containing it, but maintaining a useful fusion reaction is much more complicated than just that. As plasma courses through a reactor, it churns under the effect of several kinds of turbulence that acts on different scales. This churning is so complicated that scientists are only just starting to understand and predict it by using powerful supercomputer models.

Controlling the churn is yet another challenge, one that's lead to the development of nightmarish tangles of tech that are custom made using these calculations. They hold promise, but they're complicated, expensive, and need to be tuned just right.

Thanks to the laws of physics, you'll probably never be able to look through a glass-walled fusion reactor—real reactor techs rely on sound because they can't really see inside. But after seeing this demonstration, you can at least imagine the mind-bending science that's going on inside one.

A Part of Hearst Digital Media
Popular Mechanics participates in various affiliate marketing programs, which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites.